This study explores the possibility that spike-firing mode may represent a kind of behavioral state in individual neurons. It will investigate regulation of spike-firing mode and whether regulating spike-firing mode can influence the induction of plasticity. Specifically, it will explore the role of D-type potassium current, a subthreshold activated, slowly inactivating hyperpolarizing current. Using the hippocampal slice preparation, the kinetics and distribution of D-type current will be characterized in CA1 hippocampal pyramidal neurons. Next, the question of whether D-type current can influence spike-firing mode will be asked. If spike-firing mode can be shifted toward bursting, it is intriguing to investigate whether this shift imparts a better ability to induce long-term potentiation (LTP). Experiments will be conducted to address this. Finally, it will be determined if metabotropic glutamine receptor (mGluR) activation is a physiologic mechanism of modulating D-type current and if this modulation can subsequently affect induction of LTP.